Boox Obsidian Sync: When the Android Client Writes Notes the Vault Can’t Open

The pitch is tidy. A Boox Note Air or Go 10.3 runs Android, so you install the official Obsidian client, point it at the same vault you use on the laptop, and stop exporting PDFs out of the Boox Notes app like a person who has not heard of markdown. A week later the desktop vault has a file that will not open, or opens as an empty pane, or opens as a conflict copy whose body is last Tuesday’s grocery list wrapped in a binary the editor refuses to render. The tablet still shows the note. The vault does not.

I have done this enough times to stop blaming “sync” as if it were one product. Boox is an Android tablet that would rather you use NeoReader and the vendor notebook. Obsidian is a folder of text that assumes the writer and the reader agree on what a file is. The Android client can write something the laptop’s vault cannot treat as a note. That is a different failure from “the plugin graph is too heavy for e-ink,” which is a separate tax. This one is about bytes that arrive looking like a note and then refuse to be one.

Three writers, one folder, none of them the same app

Most broken vaults I have been asked to look at were not using one writer. They were using three:

• The official Obsidian Android app, installed from Play or a sideload, talking to Obsidian Sync or to a folder Syncthing is watching.
• The Boox native Notes app, which stores a proprietary notebook and will export PNG, PDF, or a hopeful “text” that is not the markdown your templates expect.
• Whatever Boox Assistant or the vendor cloud dumped onto the PC, usually a mirror of note packages, not of Vault/Daily.

People say “I synced Obsidian from the Boox.” They mean they enabled a cloud toggle that uploaded the vendor notebook, then they dragged a PDF into the vault and wondered why Dataview could not query it. Or they opened Obsidian on the tablet, created a daily note, and also kept scribbling in the Boox notebook because the stylus latency there still feels better. Two files, one title in their head, one of them invisible to the graph.

If you want the tablet to be an Obsidian client, the vendor Notes app is not in the loop. That sentence is rude and it saves a Saturday.

What the Android client actually writes

When you stay inside official Obsidian, the happy path is a .md file plus whatever the core apps already use: canvas, base, a PNG in Attachments. The unhappy paths I keep seeing on Boox hardware are more specific than “Android is flaky.”

Zero-byte dailies after a freeze. Boox will sleep the app hard. E-ink devices are aggressive about this because the panel is the product and the SoC is the apology. Obsidian on Android writes through the Storage Access Framework more often than people who grew up on /sdcard expect. If the process is frozen mid-write, you get a file the desktop Sync client will happily download: name is right, size is zero, the tablet still has the in-memory buffer until you swipe the app away. Then both sides agree the note is empty. The vault “can’t open” it in the sense that there is nothing to open. The history, if you have it, is on the laptop from yesterday.

Conflict copies that are not markdown. Obsidian Sync’s conflict files are usually readable. Folder-based tools are messier. Syncthing, FolderSync, and Boox’s own USB transfer will happily collide 2026-09-18.md with a file named like an Android content snapshot. I have opened “notes” that were HTML from a share sheet, or a .note package with a .md extension someone added in the Files app so it would sit in the vault. Desktop Obsidian then shows a blob, or a single line of XML, or it tries to render binary as headings.

Attachments the desktop path cannot see. The Android client will store an image where the app was allowed to write, which is not always the Attachments folder your templates link to. Wikilinks that work on the tablet resolve to a file under Android/data that never entered Sync because you excluded hidden directories, or because you never granted the vault the folder you thought you granted. The note opens. The image is a broken embed. People report that as “the vault can’t open the note” because the preview looks cursed.

Properties and newer file types the laptop has not learned. A tablet on the Play Store build will create a .base or a canvas the desktop install, pinned to an older version “because plugins,” will not parse. That is not Boox-specific, but Boox users stay on old desktop builds on purpose so the theme stays calm. The tablet does not know you did that.

Obsidian Sync versus a folder you hope is the same folder

Official Obsidian Sync is the least bad transport if you are going to run the official client on both sides. It understands vault structure. It has version history. It still cannot save you from a zero-byte write, but it can often give you yesterday’s body back.

Syncthing on Boox is the setup that looks more “owned” and then silently dies when the tablet’s battery policy kills the service. You pull the USB cable a week later and the laptop receives a burst of files that were “done” on the device and never left it. Some of those files are complete. Some are the mid-write empties. Some are notes you deleted on the desktop that the tablet recreated because it never saw the delete. This is how a vault grows a graveyard of titles the graph can see and the human cannot use.

Boox’s cloud and Boox Assistant are not Obsidian Sync. They are a vendor backup of vendor data. Pointing them at a folder inside the vault trains you to believe the notebook page is a markdown file. It is not. Export is a project. Sync is a copy. Mixing the words is how PNG pages end up in Daily.

I still meet people who put the vault in a Dropbox folder, install the Dropbox app on the Boox, and let two office-sync clients fight Obsidian’s own writers. Android file watchers are not Dropbox’s best surface. You get truncated files. You get the note on the tablet and a “can’t open” on the laptop because the desktop client downloaded a stub.

The Notes app export that looks like a vault file

This is the other half of the title, and it is the one I see when someone swears they “don’t even use Obsidian on the tablet.” They write in Boox Notes because the palm rejection and the paper templates are finished products. Then they export.

Export to text is not your daily note template. You lose wikilinks. You lose YAML. You gain line breaks that depend on how the recognizer felt about your handwriting that morning. Export to PDF is a reading copy. If you drop that PDF into the vault and give it the same name as a markdown note, some themes will show a preview that looks like a page and some will refuse to open it in the editor. The graph gets a binary node. Search gets noise.

There are community pipelines — OCR out, script into .md, even git hooks — that make this livable. They are a publishing step. They are not sync. If the recognizer emits a file the desktop treats as unknown, you did not fail at Obsidian. You asked a notebook app to be a markdown client.

Storage permissions, the quiet way files become unreadable

Boox Android is still Android. The first-run dance for Obsidian is: pick a folder, hope it is the vault root, hope .obsidian is included, hope the Files picker did not land you in a subfolder named Daily so the tablet is now a second vault that Sync will not pair.

Wrong root is the most common “can’t open” that is actually “opened a different graph.” The tablet writes Projects/q3.md relative to Daily. The laptop looks in Vault/Projects. The file exists. The vault you are staring at does not contain it. People copy the path from the tablet screen into Discord and we spend ten minutes confirming they have two vaults.

The second permission failure is a vault on a microSD that remounts with a different path after a reboot. Obsidian Android sometimes creates a new empty vault at the old path. Sync then has an empty index and a full one. Which one wins depends on timestamps you did not look at.

The third is excluding .* in Syncthing so .obsidian never travels, then installing a plugin on the tablet that writes companion files the desktop theme does not expect. The note body is fine. The workspace JSON is from another planet. “Can’t open” here means the desktop app throws a toast and the user blames the markdown.

What I actually run on a Boox if the vault has to stay a vault

I treat the tablet as a constrained Android client, not as a second brain with a stylus personality.

• Official Obsidian only. No vendor notebook in the same folder. If I want paper, it stays outside the vault until I export on purpose.
• Official Obsidian Sync if the vault is the one I live in. Version history is the feature. I do not feel noble about Syncthing on a device that will murder background work.
• A short plugin list on the tablet. That is a performance story, but it is also a file-type story: the tablet should not be the first machine to create a base, a canvas, or a community binary the laptop has never seen.
• Periodic “open yesterday’s daily on the desktop” as a restore drill. If the file is empty, I restore from Sync history before I write on top of it from the tablet again.
• No Dropbox-plus-Syncthing-plus-USB. One writer protocol.

If official Sync is off the table and the tablet keeps producing files the laptop cannot use, I would rather not pretend the Boox is a live client. Take the note in the vendor app, export when you are at the desk, and file the markdown yourself. That is slower. It does not create zero-byte dailies that overwrite a week of work because a sync client trusted a timestamp.

Some people then try to make the tablet a git remote so they can see every write. On Boox, git is still a client problem: the same sleep policy, the same SAF folder, the same chance you commit an empty file with a confident message. If the next question is whether a repo is even a better fit than official Sync when the hardware refuses to behave like a workstation, that is a different comparison — git-backed e-ink notes versus Obsidian Sync — not a fix you apply from the Boox settings search box.

A small diagnostic before you wipe the vault

When a note “won’t open” after a Boox session, I do this in order:

1. On the desktop, look at file size and modified time. Zero bytes is a freeze, not a format war.
2. Open the file in a hex-aware editor or just Notepad. If you see PNG, PK zip, or XML from a .note package, you synced the vendor notebook or an export, not Obsidian’s write.
3. Check whether desktop and tablet are in the same vault root. Compare the path Obsidian shows in Settings → Files and links, not the name of the workspace.
4. Look for a conflict copy dated the same minute. Read both. Keep the one that has sentences.
5. If you use a folder sync, see whether .obsidian and Attachments actually arrived. A note that only fails its embeds is often a missing sibling, not a corrupt body.
6. Restore from Obsidian Sync history or from the laptop’s last good copy before you edit on the tablet again. The tablet will happily re-upload the empty winner.

I do not start with “reinstall Obsidian on the Boox.” Reinstalling without fixing the folder or the sleep policy just reproduces a cleaner empty file.

The decision the hardware is asking for

Buy a Boox if you want an Android e-ink slab that can run the real Obsidian client. Then constrain that client until it only writes the same kind of file the laptop already knows how to open. Or buy a Boox if you want a notebook and accept that Obsidian happens at the desk.

Do not buy it because the Play Store icon implies the vault is now portable. The Android client will write notes. Some of those notes will be empty, binary, or addressed to a folder the desktop vault does not contain. Sync will do its job: it will copy the problem to every machine you own.

I still use a Boox for reading and for short official-Obsidian edits when the laptop is the other room. I do not let the vendor notebook and the vault share a name. I do not let a background sync client be the only copy of a daily. And when a file refuses to open, I look at the bytes before I look at another plugin. The tablet is allowed to be slow. It is not allowed to invent a file format I did not agree to.